Rotary tabletting machines

ABSTRACT

In a rotary tabletting machine, the annular space occurring between the die table and the usual flange thereabove is enclosed as a material feed chamber for containing material to be tabletted, so that such material moves continuously with the die table and is involved in the minimum of directional change for filling the dies.

United States Patent Inventors Eric Forster;

Ernest Frederick Sumner, Liverpool, England App]. No. 844,525 Filed July24, 1969 Patented Mar. 2, 1971 Assignee Manesty Machines LimitedLiverpool, England Priority July 25, 1968 Great Britain 35505/68 ROTARYTABLE'l'llNG MACHINES 7 Claims, 5 Drawing Figs.

Int. Cl 83% 11/02 Field oiSearch 107/17, l6, 15; 18/ 16.5

References Cited UNITED STATES PATENTS 1,289,570 12/1918 Stokes 107/173,029,470 4/1962 Frank 107/ 1 7X 3,460,487 8/ 1969 Kibbe l07/ l 7Primary Examiner-Price C. Faw, Jr. Attorneys-Kenwood Ross and Chester E.Flavin ABSTRACT: In a rotary tabletting machine, the annular spaceoccurring between the die table and the usual flange thereabove isenclosed as a material feed chamber for containing material to betabletted, so that such material moves continuously with the die tableand is involved in the minimum of directional change for filling thedies.

PATENTED m 2|s7| SHEET 1 OF 3 \I M I INVENTORS ERIC FORSTER ERNEST F.SUMNER ATTORNEYS PATENTEBMR m SHEET 3 OF 3 INVENTORS ERIC FORSTER ERNESTF. SUMNER ATTORNEYS.

ROTARY TABLETTWG MACHINES This invention concerns rotary tablettingmachines of the type (hereinafter referred to as of the type-describedcomprising a turret rotatable about a vertical axis and shaped toprovide a horizontal circular die table having a plurality of diesarranged in a circle therearound with a lower punch projecting upwardsinto each said die from below, and to provide a flange about the dietable in which flange are slidably located upper punches aligned withrespective ones of the dies, the punches being adapted, upon rotation ofthe turret, to move relative the dies to compress particulate, granularor like material therein into tablets, and then to eject the tablets.

In the known constructions of such machines, the material to betabletted is usually supplied to the dies by means of one or morestationary filling shoes which rest on the die table and under which thesuccessive dies pass upon rotation of the turret, openings beingprovided in the bottom of the or each shoe for the material to fallthrough into the dies.

Proposals have been made for rotors, agitators or the like to beprovided in the feed shoes to ensure mobility of the material and tocontribute to proper filling of the dies, but practical experience showsthat the known stationary material feeding arrangements are generallyonly satisfactory for slow speed machines and that increase of therotational speed of the turret is accompanied by incorrect orinsufficient filling of the dies and consequently unsatisfactory orinconsistent tabletting occurs.

We believe that this unsatisfactory operation arises at least partlyfrom the fact that the dies sweep beneath the material in the fillingshoe whilst such material is stationary or effectively stationary, andeach die is in register with the shoe for only a short period of timeinsufficient for the material both to achieve the rotational movement ofthe table and, under the influence of gravity, to flow rapidly down intothe die. The present invention is based upon the appreciation thatbetter and more satisfactory die fillingcan be achieved if the materia]is able to move continuously with the die table in its rotation in ahorizontal plane, so that upon entering into the dies there is a minimumof change of direction of the movement of the material.

With this object in view, the present invention provides a rotarytabletting machine, of the type described, characterized in that theannular space occurring between the die table and the flange thereaboveis enclosedas .a material feed chamber for occupation by material to betabletted, which material can move with the die table, a deflector beingprovided within said chamber to cause at least some of the material inthe chamber to follow a path above the dies in the die table, in theregion of a die filling sector of the table.

Conveniently, the said annular space is enclosed by a circular wallprovided at top and bottom with resiliently-loaded sealing stripsengaging with the upper surface of the table and the under surface ofthe flange.

The circular wall is conveniently composed of arcuate sections.

In a preferred embodiment, the machine is a two-station machine whereineach die has a tablet formed therein during each successivehalf-revolution of the table, and each section of the wall isapproximately semicircular and mounted upon a respective stationary partof the machine by a respective mounting.

Each such mounting is preferably adjacent a respective die fillingsector of the table, and is conveniently in the form of a hollow feedblock whereby material for tabletting can be introduced into the feedchamber in the regions of the filling sectors.

The arrangement of the invention preferably also includes, above thetable at the or each filling sector, a downwardly inclined deflector thefunction of which is to tend to deflect tabletting material into thedies as the latter pass through the filling sector.

In order that the invention may be fully understood, it will bedescribed further, by way of example, with reference to the accompanyingdrawings which illustrate a preferred embodiment of the machine in theform of a two-station machine.

In the drawings:

FIG. l is a cross-sectional elevation of the entire machine;

FIG. 2 is an enlarged fragmentary detail of part of the machine of PEG.1',

FIG. 3 is a fragmentary sectional plan corresponding to FIG. 2, theposition of the section having been indicated by the lines IIIIII inFIGS. I and 2;

FIG. 4 is a fragmentary section, as indicated by the line IV-IV of FIG.3, to a more enlarged scale, showing further details of the machine; and

FIG. 5 is a detached elevation showing part of FIG. 4 when viewed asindicated by the arrow V.

The illustrated machine, in general overall constructions, resemblesknown two-station rotary tabletting machines in that it comprises asupporting framework 10 wherein is journaled a vertical turret shaft 11on which a turret 112 is secured, an appropriate drive motor 13 beingprovided for driving the turret 12, by way of a drive belt 14, pulleyl5, worm shaft 16, worm wheel 17, drive shaft 18 and drive pinion 19which meshes with a gear ring 20 set into an annular recess in theunderside of the turret 12, and thereby rotating the turret 12 about avertical axis.

The turret I2 is shaped to provide a substantially horizontal circulardie table 21 having an array of die holes 22 vertically therethrough,these die holes 22 being arranged on a circle around the rotational axisof the turret 12 (see FIG. 3) and each accommodating a respectivetabletting die 23 which is in the form of a hard metal sleeve of shortaxial length. A respective lower punch 24 projects upwards from belowthe die table 21 into each of the dies 23, such punches 24 beingaccommodated for vertical sliding movement in respective holes in anannular skirt 25 of the turret 12.

The turret i2 is also shaped to provide, above the die table 2i, aflange 26 which overhangs the circle of dies 23 and has therethroughupper punch holes each of which accommodates a respective upper punch 27which is axially aligned with a respective one of the dies 23.

Cam tracks 28 and 29 are provided for engagement by enlargements orprotrusions 30 and 31 on the lower ends of the lower punches 24 and onthe upper ends of the upper punches 27, for causing axial up and downmovement thereof and effecting the necessary punch movements associatedwith tabletting operations and at each of two diametrically opposedpositions (which correspond to two tabletting stations of the machine)there are upper and lower pressure rolls 32,33 between which thecorresponding pairs of punches 27 and 24 pass so that endwise pressureis applied to the successive pairs of punches 27,24 to apply tablettingpressure to tabletting material in the corresponding die 23.

The parts as so far described are comparable with prior known machines.The machine of the invention differs from the known machines, however,in the means provided for supplying tabletting material to the dies 23.

With the turret construction as above discussed, there is, naturally, anannular gap 34 occurring in the turret l2 between the undersurface ofthe flange 26 and the upper surface of the die table 2ll. In the machineof the invention, this gap or space 34 is employed as a tablettingmaterial feed chamber, and this is achieved by enclosing the spaceconcerned, making provision for feeding tabletting material thereto, andmaking provision for ensuring that at least part of any material in suchspace 34, upon rotation of the die table 21, is constrained to move overthe dies 23 for filling the latter.

To achieve this, two feed chamber wall sections (of which one isillustrated in its entirety and is indicated generally by referencenumeral 35 in FIG. 3) are provided, and since these sections aresubstantially identical one thereof needs to be described in detail. Thewall section 35 comprises two side-byside metal strips 36 and 37 ofwidth just less than the vertical spacing between the die table 21 andthe flange 26, which strips are curved to approximately semicircularform so that each resembles one-half of a cylinder of short axiallength. The radii of curvature of the strips are somewhat less than theradius of the circle in which the dies 23 are arranged around the dietable 21.

The two side-by-side strips 36 and 37 are rigidly secured to oneanother, at appropriate intervals, by rivets 38 with the result that thewall section 35 may be regarded as being l-I- shaped in cross section,providing narrow upper and lower channels each of which accommodates arespective nylon scraper blade 41,42. A sinuous spring 43, accommodatedbetween the strips 36,37 and abutting against the confronting edges ofthe blades 41 and 42, serves to load such blades 41,42 so as to protrudefrom their respective channels in the wall section 35. As can be seenfrom FIG. 3, the blades 41,42 may be composed of a plurality ofsections.

The wall section 35, is secured, by way of the strip 36, to a curvedopen side 44 of a saddle-shaped hollow feed block 45 the general shapeof which can best be seen from FIG. 3. This feed block 45 is flat on itsunderside for mounting on a mounting plate 46 in turn mounted upon arespective appropriate support column 47 provided on the frame of themachine and to project a short distance over the die table 21, as can beseen from FIGS. 1 and 3, so that the curved side 44 of the feed block 45follows, but just lies inside the path of movement of the dies 23therepast. As already mentioned, the feed block 45 is hollow; it has aninlet connection 48 joining with its top and an outlet opening 49 in itsbottom, such outlet opening 49 being generally of arcuate form andoverlying a number of the dies 23 in the die table 21 as can be seen inFIG. 3.

The lower scraper blade 42 and the lower parts of the strips 36,37 arerelieved or gapped in register with the outlet opening 49, as indicatedat 50 in FIG. 1, to permit material to flow from the interior of thefeed block 45, through the open side 44 thereof and the gap 50, into theannular gap 34 which forms the feed chamber of the machine. Securedwithin the feed block 45, by screws 51 is an inclined deflector plate 52which projects through the gap 50 into the feed chamber 34 and is formedtherein with a lead-in tongue 53, the edge 56 of such plate 52 remotefrom the tongue 53 being close to the upper surface of the die table 21.

The two wall sections 35, of which one has just been described, areappropriately mounted by their feed blocks 45 being secured on theirmounting plate 46, which are at diametrically opposed positions,relative to the turret 12, so that the feed blocks 45 are in advance oftheir corresponding pressure roll pairs 32,33, and the upper and loweredges of the wall sections 35 seal respectively with the lower surfaceof the flange 26 and the upper surface of the die table 21 by theirscraper blades 41,42. Each of the wall sections 35, together with itsfeed block 45, extends around one-half of the turret 12. A finishedtablet deflector 54- is provided on one side of each feed block 45, andthese are associated with respective tablet takeoff chutes 55 thepositions of which are indicated diagrammatically in FIG, 1.

Each feed block 45 has a funnellike hopper 56a secured to its inletconnection 48 and material (not shown) to be tabletted is supplied tothe feed chamber 34 between the flange 26 and the die table 21 by beingfilled into the hopper 56a to fall into the interior of the feed block45 and pass through the curved open side 44 thereof. Material present inthe block 45 can also rest on the die table 21 by way of the outletopening 49.

Assuming the hoppers 56a to have been filled with tabletting materialand the turret 21 being driven, material from the hopper 56a and fallingonto the die table 21 both above the dies 23 and in the feed chamber 34is entrained by the die table 21 and with continued running of themachine the feed chamber 34 becomes substantially full of tablettingmaterial which is largely constrained to move with the table 21, so thatthe tabletting material, once it has entered the feed chamber 34 may beregarded as having no substantial relative movement in relation to thedie table 21 so far as the rotation of the latter in a horizontal planeis concerned,

For understanding the actual operation of the machine, it is mostconvenient to consider one only of the dies 23 during a completerevolution of the turret 12, the other dies 23 following successivelyand correspondingly.

At the commencement of the entire tabletting cycle, the upper punch 27is raised clear of the die 23 and the lower punch 24 is raised to aposition wherein its top face is just flush with the top surface of thedie table 21, this position of the lower punch 24 being necessary forthe removal of a previously formed tablet. As the turret 12 rotates, thedie 23 moves towards a first die filling sector of the table 21, whichsector corresponds to the outlet opening 49 in a first one of the feed Iblocks 45 and during this movement the upper punch 27 is retained in itsraised disposition, whilst the lower punch 24 effects slight downwardmovement. As it approaches the filling sector of the first feed block45, the die 23 moves beneath the deflector plate 52 thereof and withcontinued movement the deflector plate 52 and the tongue 53 thereofdeflect tabletting material carried on the die table 21 firstly radiallyoutwards of the die table 21 the path of the die 23 and then down intothe die 23, at the same time as the lower punch 24 is moved downwards toencourage the die 23 to fill. The die 23 accordingly passes the loweredge 56 of the deflector plate 52 at least partially filled withtabletting material, and now moves past the bottom of the inletconnection 48 where the latter connects with the feed block 45. At thisposition, the space above the die 23 is partly unoccupied by tablettingmaterial by reason of the die 23 having been partially filled, and freshtabletting material can enter the feed block 45 through the inletconnection 48 to flow into the die 23 as it passes and/or to causemovement of material already in the feed block 45 into the die 23 tofill the latter, the lower punch 24 by now being fully lowered.

With continued movement of the die 23, and whilst still in the region ofthe feed block 45, the lower punch 24 now moves upwards slightly toreduce the filled volume of the die 23, thereby effecting so-calledweight-adjustment by ejecting upwards out of the die 23 any tablettingmaterial exceeding a predetermined amount. The die 23 now passes towardsthe respective end of the first feed block 45 adjacent which scrapers 57and 58 project inwardly over the die table 21 to sweep inwards of thedie table 21 any (jected or other tabletting material overlying the die23 or disposed between the die 23 and the outer edge ofthe die table 21.

The die 23 then passes under a tail plate 59 which projects from therespective end of the feed block 45, and the upper punch 27 commencesmoving downwards. As the die 23 (which is now disposed, relative to thedie table 21, outside the feed chamber 34) emerges from under the tailplate 59, the upper punch enters the die 23 from above and slightinitial pressure is applied to the tabletting material from above andbelow, by way of the two punches 24,27 under the influence of their camtracks 28,29. With continued rotation of the turret 12, the two punches24,27 now move between the pressure rolls 33,32 whereat considerableendwise pressure is applied to the punches 24,27 to tend to move themtowards each other and compress the material in the die 23 into acoherent tablet 60 (FIG. 4).

This having been done, the upper punch 27 is raised by continuedmovement of the turret 12, until it is back at the position occupied atthe beginning of the cycle and the lower punch 24 is similarly raised tobring the tablet 60 to an ejection position as shown in FIG. 4 whereinits lowermost surface is flush with or just above the upper surface ofthe die table 21.

The die 23 and tablet 60 are now moving towards the feed block 45 of thesecond station of the machine, the table 2t having performed half arevolution, for the commencement of a second tabletting cycle which isidentical with that just described during the second half of thecomplete revolution of the turret. As the die 23 approaches the secondfeed block 4-5 'deflector plate 52 of the second feed block 45 at thecommencement of the second tabletting cycle.

We have found that with such an arrangement, it is possible to increasethe speed of the tabletting machine, as compared with the running speedsof prior known comparable rotary tabletting machines, as much as twofold, whilst still achieving satisfactory reliable andconsistenttabletting and without experiencing the deficiency indie-filling which has been encountered when attempts have been madematerially to increase the running speeds of the prior known machineshaving shoelike or similar feeders. We attribute this achievement to thefact that the arrangement of the invention provides for substantiallyall, or at least a large proportion, of the tabletting material presentin the feed chamber 34 and available for filling the dies 23 to beconstrained to move with the die table 21 as compared with the knownstationary feed arrangements wherein the tabletting material iseffectively initially stationary relative to the die table and has tocatch up with the speed of rotation of the die table at the same time asfalling into the dies, for filling the latter.

The invention is not confined to the precise details of the foregoingexample and variations may be made thereto. For instance, if desired,radial vanes or the like may be provided in the feed chamber (e.g.projecting outwardly from a ring surrounding the hub or center of theturret) to ensure that the tabletting material is positively caused tofollow the rotation of the die table rather than reliance being placedupon the fric- 1. A rotary tabletting machine comprising a turretrotatable about a vertical axis shaped to provide-a horizontal circulardie table above which is a flange, said flange and said die' tabledefining between them an annular space around said turret, a pluralityof dies arranged in a circle around said horizontal die with each ofsaid dies, wall means enclosing said annular space as a material feedchamber for occupation by material to be tabletted, whereby saidmaterial will move with said die table upon rotation of said turret,deflector means in said material feed chamber to cause at least some oftabletting material therein to follow a path over the dies in said dietable, in the region of a die filling sector of said table, actuatingmeans constraining said upper and lower punches to move relative to saiddies so as to cause each said upper punch to be raised clear. of itssaid die upon its said die approaching said filling sector, to causeeach said lower punch to be lowered as its said die moves in saidfilling sector for tabletting material to fill into said die, to bringsaid upper punch down into its said die upon the latter moving out ofsaid filling sector, to apply endwise pressure to said upper and lowerpunches to compress said material in said die to form a tablet, to raisesaid upper punch and said lower punch to eject said tablet from saiddie.

2. A machine as set forth in claim 1 wherein said wall means comprises acircular wall provided at top and bottom with resiliently loaded sealingstrips engaging respectively with the upper surface of said die tableand the lower surface of said flange.

3. A machine as set forth in claim 2 wherein said circular wall iscomposed of a plurality of arcuate wall sections.

4. A machine asset forth in claim 3 which is a two-station machinewherein each said die has a tablet formed therein during each successivehalf-revolution of said die table, characterized in that each saidarcuate wall section is semicircular.

5. A machine as set forth in claim 4 further including, for each saidwall section, a mounting located at the respective said filling sector,

6. A machine as set forth in claim 5 wherein each said mountingcomprises a hollow feed block, supply means, whereby tabletting materialmay be supplied to said feed block, being connected to said feed block.

7. A machine as claimed in claim 6 further including, con nected to saidfeed block, a downwardly-inclined deflector disposed to deflectmaterial, in said feed block downwards table, a lower punch projectingupwards into each of said dies, into said dies as P through Said fillingSectoran upper punch slidably located in said flange in alignment

1. A rotary tabletting machine comprising a turret rotatable about avertical axis shaped to provide a horizontal circular die table abovewhich is a flange, said flange and said die table defining between theman annular space around said turret, a plurality of dies arranged in acircle around said horizontal die table, a lower punch projectingupwards into each of said dies, an upper punch slidably located in saidflange in alignment with each of said dies, wall means enclosing saidannular space as a materiaL feed chamber for occupation by material tobe tabletted, whereby said material will move with said die table uponrotation of said turret, deflector means in said material feed chamberto cause at least some of tabletting material therein to follow a pathover the dies in said die table, in the region of a die filling sectorof said table, actuating means constraining said upper and lower punchesto move relative to said dies so as to cause each said upper punch to beraised clear of its said die upon its said die approaching said fillingsector, to cause each said lower punch to be lowered as its said diemoves in said filling sector for tabletting material to fill into saiddie, to bring said upper punch down into its said die upon the lattermoving out of said filling sector, to apply endwise pressure to saidupper and lower punches to compress said material in said die to form atablet, to raise said upper punch and said lower punch to eject saidtablet from said die.
 2. A machine as set forth in claim 1 wherein saidwall means comprises a circular wall provided at top and bottom withresiliently loaded sealing strips engaging respectively with the uppersurface of said die table and the lower surface of said flange.
 3. Amachine as set forth in claim 2 wherein said circular wall is composedof a plurality of arcuate wall sections.
 4. A machine as set forth inclaim 3 which is a two-station machine wherein each said die has atablet formed therein during each successive half-revolution of said dietable, characterized in that each said arcuate wall section issemicircular.
 5. A machine as set forth in claim 4 further including,for each said wall section, a mounting located at the respective saidfilling sector.
 6. A machine as set forth in claim 5 wherein each saidmounting comprises a hollow feed block, supply means, whereby tablettingmaterial may be supplied to said feed block, being connected to saidfeed block.
 7. A machine as claimed in claim 6 further including,connected to said feed block, a downwardly-inclined deflector disposedto deflect material, in said feed block downwards into said dies as theypass through said filling sector.